This proposed body of research seeks to characterize and quantify the mechanisms by which executive processes direct and coordinate underlying, more automatic information processing systems. Behavioral, psychophysiological and computational methods will be used to observe, predict and model these executive attentional processes in normal subjects. The ability to process information from both tasks of a dual-task pair in parallel without being limited by a central bottleneck will be investigated in light of recent data, and the conditions under which such parallelism may occur will be determined An attentional dual-task framework will be used to investigate issues of parallel semantic and phonological processing in language production, and psychophysiological methods will be used to examine neural evidence of parallel response-selection processing. The attentional control of single- and dual-tasks by the executive will be investigated in terms of Task Sets and their parameters, using experimental behavioral measures as well as predictive computational modeling. The nature and properties of Task Sets as specific sets of executive attentional parameters will be examined. A computational theory of executive attentional control of behavior will be developed, expanding on and refining Logan and Gordon?s Executive Control Theory of Visual Attention (ECTVA) model. This work addresses key issues of executive control and central information processing which underlie many other areas of cognitive science. This basic research seeks to provide a strong theoretical and empirical formulation of normal executive and attentional function, from which future studies of disordered attentional and executive functions, such as Attention-Deficit/Hyperactivity Disorder and Alzheimer?s Disease, may proceed.